In manufacturing medicaments for sale, the medicaments are often packaged in containers of convenient quantities. For example, 100 pills may be packaged in a bottle while another bottle may be available containing 250 pills.
One type of prior art dispensing machine for filling these containers is conventionally referred to as a slat filler. In a slat filler the articles such as pills are fed into open cavities formed in an elongated bar, called a slat. The slat is moved along a conveyer to a discharge station where it is tilted for gravity discharge of the articles from the cavities into the containers.
In a slat filler the slats are supported for movement along a continuous, endless closed loop. They move in a direction which is transverse to the elongated slat members. The outer surfaces of the slat members are provided with a plurality of spaced apart cavities which travel along the endless path past filling and then discharging stations. Upon reaching the discharge station, each slat member tilts for simultaneous discharge of all the articles from its cavities.
The containers are automatically positioned by a conveying system below the discharge station along a path below and parallel to the tilting slat members. The falling articles are guided by chutes as they fall out of the cavities of the slats and into the containers. The moving slats are counted or other means is provided for signalling that a selected number of slats have emptied their contents into the containers. After a selected number of slats have dumped their contents into containers an index occurs and the containers are moved from beneath the chutes and are replaced with empty containers to continue the filling process.
Slat filling machines of this general type are manufactured by the Lakso Company and are illustrated in U.S. Pat. Nos. 4,017,003; 3,354,607; and 3,925,960 and in application Ser. No. 46,191 filed June 6, 1979.
One problem which has been experienced with such slat type filling machines is that a cavity may not have an article in it as it approaches the discharge station. Without an inspection apparatus, the absence of an article will result in some particular container having one article fewer than the quantity which is labelled on the container and for which the customer will pay. Therefore, one purpose of the present invention is to continuously inspect these cavities to detect the absence of an article from a cavity and to automatically eject a container which is short filled as a result of this absence.
We have previously constructed an inspection system in which light energy, ordinarily in the infrared portion of the electromagnetic spectrum, is radiated from a series of photoradiators at each cavity. The radiation source consisted of a series of photodiodes, one positioned in alignment with each cavity. A corresponding series of cooperating photodetectors was positioned on the opposite side of each slat having one detector aligned with each cavity to receive any light which passes through the cavity. In this way the presence of light at a detector indicates the absence of an object in the cavity and the absence of light at the detector indicates the presence of an object in the cavity. In such a system each radiator/detector pair is dedicated to a single cavity of a slat.
The difficulty with that system is that slat-type filling machines ordinarily are capable of using a variety of slats to accomodate different object or pill sizes and different container quantities. Therefore, a variety of interchangeable slats are used in a slat filling machine each differing from the others in the spacing and positioning of the cavities. This variety necessitated the manufacture of a different unique pair of radiator head and a mating detector head, one pair corresponding to the appropriate cavity alignment for each of the possible slats. Then, each time the slats were changed for a different production run the heads had to be changed.
The present invention overcomes this difficulty by providing a single photoradiator array mounted on a single radiator head and a single detector array mounted on a single detector head. This one pair can be used for all of the slats which might be used thus requiring no modification or changing of these parts as the slats are changed and the machine is used for different production runs of different objects or pills.